My hamper floweth over

We have a little electronic keyboard that has pre-programmed songs. Pierce and Lillian's favorite new game is to shout a name at the keyboard, press the button that plays "Happy Birthday", and then laugh hysterically when the keyboard "says" that name. HOW DOES IT KNOW?!? Confused? They sing the song in their head, of course saying the name they just shouted, so to them it sounds like the keyboard is singing "guinea pig" or "Maxwell", or any other of the names they say, when it is actually their little brains that is saying it. I need to get a video, it's very funny!